A friend of mine just picked up a near-mint 1976 KZ 400. He had new tires put on, and had the brakes checked, etc. But then asked me to help find the rubber manifold carb boots for both sides of the carbs. Airbox to carb, and carb to engine. I thought it would be easy to go online and find some,, but I have not bumped into any yet.
Anyone have a secret source for NOS Kawasaki parts? I did find some part numbers:
airbox to carb left 11015-042, airbox to carb right 11015-043, both carbs to engine 16065-037 or maybe 16065-048.

the aircleaner duct is #11015-062, and the engine intake duct is #16065-048.

the site also says what other models use the same part number. the engine intake duct is also used by the 1977-79 KZ650 custom model.

according to bikebandit.com, their part number is 752914 for the aircleaner duct ($7.90 each) and 781729 for the engne intake duct ($24.80 each). i called them, but their 1-888 number dont work in canada.

i've printed and bound the parts diagrams from kawasaki.com. great reference material.